The present invention relates to a structure of a carriage in an aerial transport system, such as an aerial tramway or cableway system. More specifically, the invention relates to a suspension structure for suspending a carriage from the aerial track of the transport system.
For simplification of the description, the word "carriage" is intended to include not only the carriage per se but also the vehicle, and the work "cableway" is intended to include not only the cableway but also a tramway.
As is well-known, there have been various aerial cableway systems for transporting passengers and/or articles along long mountain ascents and descents, and over canyons and rivers. Such cableway systems have also been applied to automatic manufacturing lines in factories.
Such a cableway system generally comprises an aerial track suspended by two or more stationary towers and defining the cableway, and one or more carriages travelling along the track. The carriages are suspended from the track by means of various suspension members. The suspension members generally comprise a hanger, its upper end connected to a beam, and frames holding pairs of wheels and provided on opposite longitudinal ends of the beams. The running wheels ride on the track and rotate to move the carriage along the track. The carriage is suspended for rotation about yaw axes and pitch axes.
In FIGS. 1 and 2, there are illustrated well-known typical constructions of suspension structures suspending the carriage from the aerial track. FIG. 1 shows a suspension structure in which a carriage body 5 is suspended from an aerial track 7 by a suspension member 8 including a pair of frames 2 respectively holding pairs of running wheels 3. The frames 2 are connected to a beam 1 for rotation in the yaw direction about vertical axes "Y.sub.1 " with respect to the beam 1. A hanger 4 is connected to the beam 1 for rotation about an axle 6 in the pitch direction with respect to the beam 1 and perpendicular to the track 7. Since the carriage body 5 is fixedly secured to the lower end of the hanger 4, it cannot move with respect to the hanger in any direction and thereby subjects the joining portion therebetween to a concentration of load.
With this construction, as each pair of wheels 3 are held or supported rotatably about horizontal axes on the frame 2 so as to rotate together with the frame 2 with respect to the beam 1 and if curvature of the track is smaller than the allowable minimum curve radius which may be determined in accordance with the distance between the pair of wheels held on the common frame 2, the carriage cannot travel through the curved portion of the cableway. Therefore, the minimum radius of curvature of the track 7 is restricted due to the distance between the wheels on the same frame.
While, in such a construction of the suspension structure, the frames 2 are fixedly connected by the rigid beam 1 and cannot rotate in the pitch direction with respect to the beam 1 to possibly cause the beam to be subjected to vertical distortion when elevations of the respective frames are different. This may result in shortening the lifetime of the beam. Further, upon travelling of the carriage through the curvature of the track, respective wheels are subject to rotational moment to cause an increase in friction between the wheels and the track. Thus, the lifetime of both the wheels and track are substantially shortened. Yet further, since in such a construction, the carriage has a rigid beam of substantially heavy weight above the track, the carriage does not have the desired sufficient stability.
FIG. 2 shows another typical construction of the suspension structure for suspending the carriage from the aerial track. A carriage body 15 is suspended from an aerial track 17 by means of a suspension member 18. The suspension member 18 comprises a rigid beam 11, frames 12 rotatably connected to both longitudinal ends of the beam 11 and a hanger 14. Each frame is provided with a pair of running wheels 13 rotatable about substantially horizontal axles 19 of the frame 12 to travel along the track 17. Each frame 12 is rotatable in the yaw direction "Y.sub.2 " and the pitch direction P.sub.2 around axle 19 with respect to the beam 11. The hanger 14 is rotatably suspended, with respect to the beam 11, about axis "Y.sub.3 ". Also in this construction, the carriage body 15 has no freedom of motion with respect to the hanger 14.
Since such construction allows the frame 12 to rotate in the pitch direction, with respect to the beam 11, it can eliminate vertical distrotion due to a vertical movement of bending subjected to the beam 11. However, there remains a problem that since, in such a construction a rigid beam of substantially heavy weight is employed, it may cause bringing upwardly the gravity center of the carriage so as to make the same unstable.
Further, in both constructions as above-mentioned, the hangers 4, 14 and the carriage bodies 5, 15 are respectively fixed together and therefore, static and dynamic loads are applied to the joining portion between the hanger and carriage body. In particular, the concentration of static and dynamic load is extreme when the carriage goes up or down a slope, or the load is uneven. It should be noted that the static load on the joining portion between the carriage body and hanger is generally caused by the gravity of the carriage and whatever is contained therein, while the dynamic load being subjected to the joining portion is caused in general directions.
Further, reinforcement of the joining portion against the concentration of the load is required to have a strong structure which unavoidably increases the weight. The reinforcement has been required not only for the joining portions but also for respective segments of the suspension members as well as the track. This may result in a substantially high cost for the cableway system.
Still further, when two or more carriages 15 of FIG. 2 are trained together, the respective frames 12 are connected with a traction link 16, as shown in FIG. 3. However, if the carriage ascends or descends a slope, the carriage swings in a substantially pitch direction about the pivoting points 21 of the hanger 14 with respect to the beams 11, as shown by dotted lines in FIG. 3. This may cause the carriage bodies 15 to collide. Thus, a sufficient interval to prevent collision between the carriage bodies 15 is required for safety. Since the interval between the carriage bodies 15 is substantially longer, the connecting link which forms a chord between the leading and trailing carriages when they run on a curved track is thus also lengthened. Consequently, the radius of the track becomes too small and it is impossible for the carriage to run thereabout and the turning curvature of the track becomes limited and shortens the radius of the curvature.
It would be possible to eliminate the problem of the carriages colliding with one another on an ascending slope or due to inertial running of the trailing carriage by employment of a rigid link 22, as shown in FIG. 4. However, the rigid link 22 causes the carriage bodies to tilt or rotate out of line when moving along a slope, as shown by the dotted line in FIG. 4. This tilting or moving out of line results in loosening of the containers or in the discomfort or danger to the passengers in the carriage bodies.
The present invention is to remove drawbacks and disadvantages as those above-mentioned which have characterized previous suspension structures, and more particularly to provide an arrangement for suspending an aerial cableway or carriage which reduces the weight above the track, increases stability of the carriage and when several carriages are linked together prevents collision of adjacent carriages.